采用甲酸铝对硫酸铝基无碱液体速凝剂进行改性,并测试了甲酸铝改性后的无碱液体速凝剂性能指标.采用XRD、SEM、TG-DTG和水化热分析表征手段分析了甲酸铝改性硫酸铝基无碱液体速凝剂对水泥水化过程的作用机制.结果表明:随着硫酸铝基无碱液体速凝剂中甲酸铝掺量的增加,水泥的快凝效果和强度均呈先增大后减小的趋势;当改性组分甲酸铝掺量为1％(以硫酸铝质量百分比计)时,掺8％改性硫酸铝基无碱液体速凝剂的水泥初凝时间为2 min 39 s,终凝时间为5 min 33 s,1 d抗压强度为13.2 MPa,28 d抗压强度为49.6 MPa,28 d抗压强度比为114％,90 d抗压强度保留率为123％,满足《喷射混凝土用速凝剂》(GB/T 35159-2017)标准的技术指标要求.当改性组分甲酸铝掺量超过1％时,生成的大量AFt会抑制水泥中C3S的水化反应,导致水泥早期和后期强度降低.
Abstract
Aluminum formate was used to modify aluminum sulfate based alkali-free liquid accelerator,and the performance index of alkali-free liquid accelerator modified by aluminum formate was tested in this paper.XRD,SEM,TG-DTG and hydration thermal analysis were used to analyze the effect of aluminum sulfate based alkali-free liquid accelerator modified by aluminum formate on the hydration process of cement.The results show that with the increase of aluminum formate content in aluminium sulfate based alkali-free liquid accelerator,the quick setting effect and strength of cement show a trend of increasing first and then decreasing.When the modified content of aluminum formate is 1％(based on the mass percentage of aluminum sulfate),the properties of cement with 8％modified aluminum sulfate based alkali-free liquid accelerator are as follows:initial setting time of 2 min 39 s,final setting time of 5 min 33 s,1 d compressive strength of 13.2 MPa,28 d compressive strength of 49.6 MPa,28 d compressive strength ratio of 114％,and 90 d compressive strength retention rate of 123％,which meets the technical index requirements of the standard"Flash setting admixtures for shotcrete"(GB/T 35159-2017).When the modified content of aluminum formate exceeds 1％,a large amount of AFt inhibits the hydration reaction of C3S in cement,resulting in the early and late strength reduction.
关键词
甲酸铝/硫酸铝/无碱液体速凝剂/改性机制/喷射混凝土/凝结时间
Key words
aluminum formate/aluminum sulfate/alkali-free liquid accelerator/modification mechanism/shotcrete/setting time
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